Using Charles Proxy to load scripts into other webpages

charles-proxy-rewrite-settings.xml

<?xml version='1.0' encoding='UTF-8' ?>
<?charles serialisation-version='2.0' ?>
<rewriteSet-array>
  <rewriteSet>
    <active>true</active>
    <name>Script Loader</name>
    <hosts>
      <locationPatterns>
        <locationMatch>
          <location>
            <host>*.*</host>
          </location>
          <enabled>true</enabled>
        </locationMatch>
        <locationMatch>
          <location>
            <protocol>.*</protocol>
          </location>
          <enabled>true</enabled>
        </locationMatch>
      </locationPatterns>
    </hosts>
    <rules>
      <rewriteRule>
        <active>true</active>
        <ruleType>7</ruleType>
        <matchValue>(&lt;/[Hh][Ee][Aa][Dd](&gt;|\s))</matchValue>
        <matchHeaderRegex>false</matchHeaderRegex>
        <matchValueRegex>true</matchValueRegex>
        <matchRequest>false</matchRequest>
        <matchResponse>true</matchResponse>
        <newValue>&lt;script data-provider=&quot;script-loader-proxy&quot; type=&quot;text/javascript&quot; src=&quot;//localhost/charles-script-load/loader-script.js&quot;&gt;&lt;/script&gt;</newValue>
        <newHeaderRegex>false</newHeaderRegex>
        <newValueRegex>false</newValueRegex>
        <matchWholeValue>false</matchWholeValue>
        <caseSensitive>true</caseSensitive>
        <replaceType>1</replaceType>
      </rewriteRule>
    </rules>
  </rewriteSet>
</rewriteSet-array>

loader-script.js

// Served from localhost with Charles
(function () {

  var scripts = [
    'localhost/repos/repo1/src/repo1.js',
    'localhost/repos/repo2/src/repo2.js'
  ];

  scripts.forEach(function (url) {
    var script = document.createElement('script'),
    first = document.getElementsByTagName('script')[0];
    script.src =  document.location.protocol + '//'+ url;
    script.type = 'text/javascript';
    script.async = true;
    first.parentNode.insertBefore(script, first);
  });

})();